This invention relates generally to agricultural harvesting equipment, and more particularly to an improved wheat harvesting combine.
Combines have for many years been used to harvest wheat. They may be either of the self-propelled type in which the propulsion unit is a part of the combine, or may be designed to be pulled by a tractor or other vehicle. In any event, combines typically include a sickle which has a multiplicity of reciprocating cutting teeth, and a header which defines a trough and a rotary shaft or auger which collects the cut wheat and feeds it to a central or laterally offset feeder. The feeder then feeds the wheat rearwardly through a threshing/separating system which separates the grain from the rest of the plant, and the grain is accumulated in a grain tank.
Pulled combines are typically of cantilevered construction with the feeder housing being positioned at one lateral end of the header. This is desirable, if not necessary, because the pulling vehicle should be disposed to one side of the combine so that the wheat which is being harvested is not matted down by the wheels of such vehicle. This cantilevered construction normally limits the length of the header and therefore the width of swathe which is being cut. Self-propelled combines, which centrally support the header, permit wider swathes to be cut but are far more expensive than pulled combines because an entire propulsion system, including an operation station, must be included.
Another important design consideration with combines is the extent to which the header follows undulations in the terrain which is being traversed. Some combines are designed exclusively for use on relatively flat terrain. Other combines, commonly know as hillside combines, are designed to follow substantial changes in the terrain. Such combines, which are typically self-propelled, are normally provided with a so-called circle which is mounted adjacent the feeder housing to permit relative rotation between the feeder housing and the header. Because the feeder housing is, with such self-propelled combines, centrally located rather than at one lateral end or the other of the header, upward movement of either end results in downward movement at the other end. This is undesirable because it results in uneven cutting.
Some types of combines, such as belt pick up types, include a wheel adjacent each end of the header. This is possible with a pick up combine because it is merely picking up the wheat which has been cut. With direct-cut headers which simultaneously cut and pick up the wheat, such wheels would not be permissible because one of the wheels would be rolling over wheat which has not yet been cut.
There have been many prior attempts to design header support systems which permit the length of the header to be increased. One such design is presented in U.S. Pat. No. 4,359,854 to Witzel. This patent discloses an outrigger-type support having a plurality of wheels behind the header of a pulled combine. Another Witzel patent, U.S. Pat. No. 4,329,833, discloses a self-propelled combine in which the feeder housing is centrally disposed on the header, and a plurality of outrigger-type wheeled supports are provided on each side of the propulsion unit. In both Witzel patents the header is permitted to swivel upwardly and downwardly along a horizontal, longitudinal axis as the header passes over undulations in the contour of the ground. Both headers are also mounted to swivel about a vertical axis so that they may be swung out of the way for roadway travel. However, the means by which the header is mounted to the outrigger-type supports it is not adequately disclosed and does not appear to permit the vertical movement which would normally take place as the header is pivoting. The combines disclosed in the Witzel patents are also relatively complicated, resulting in substantial initial and operating costs.
Yet another drawback of the combine disclosed in U.S. Pat. No. 4,359,854 is that a driven chute must be disposed between the header and the feeder to convey wheat therebetween. This presents an obstruction in the flow of wheat and requires additional energy input.
It is therefore an object of the present invention to overcome the drawbacks and limitations of the prior art proposals. More specifically, the invention has as its objects the following: (1) to provide a pulled combine having a header which is as wide as those of the self-propelled type, thereby dramatically increasing the rate at which wheat can be harvested; (2) to develop a combine which is suitable to operate on either flat or hilly terrain; (3) the provision of a pulled combine which has sufficient structural integrity that it may be used with rough terrain without maintenance problems; (4) to provide a combine which permits the header to be pivoted with respect to the feeder housing without adverse stress occurring in the components thereof; (5) to provide a combine in which wheat is permitted to flow directly from the header into the feeder housing without requiring the use of any intermediate drive means; and (6) to develop a hillside, pulled combine which is easily adjustable to different cutting heights without requiring complex drive cylinder arrangements, cables, or the like.